The drug and pesticide metabolizing microsomal monoxygenase system will be studied in three insect species, the house fly (M. domestica), the blow fly (P. regina), and the flesh fly (S. bullata). Microsomal membranes obtained from homogenates of the insects will solubilized by treatment with detergents and the essential components of the system, cytochrome P-450, cytochrome P-450 reductase, and a phospholipid fraction, will be isolated and purified. These components will then be studied alone and in combination to learn their chemical and enzymatic characteristics. Of principal interest will be the number of forms of cytochrome P-450 present in immature and mature stages of each species, their substrate specificities, their response to chemical inducers and inhibitors and their differences in insecticide resistant and susceptible strains. The comparative biochemistry of these microsomal components in the three species will also be studied. The overall objective of the research is to understand the nature and function of these enzymes and to used this knowledge in the development of better methods of insect control.